/**
 * Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).
 * For example, this binary tree [1,2,2,3,4,4,3] is symmetric:But the following [1,2,2,null,3,null,3] is not:
 * 
 */
/**
 * @author Ivan
 *
 */
package problem101_Symmetric_Tree;